Turbo coding is employed with space-time spreading (STS) transmission to improve transmission error performance and efficiency in addressing multipath fading. Different subsets of parity data are transmitted via each antenna/channel, with either subset alone sufficient for error recovery. In general, however, both channels will be received with some fidelity, and the parity data from the two channels is combined and decoded as a lower code rate transmission. Systematic data may be transmitted on both channels, with or without interleaving on an alternate channel. Time diversity may also be introduced by transmitting only part of the parity data within the two parity data subsets, then transmitting the remainder if the receiver could not produce the correct decoding from the original transmission.
Legal claims defining the scope of protection, as filed with the USPTO.
1. For use in a wireless communications system, a system for turbo encoding with transmit diversity, said system comprising: first and second physically displaced antennas sufficiently spaced to produce substantially independent fading of signals received at a receiving station; a first encoding unit coupled to said first antenna, said first encoding unit receiving systematic data and generating first and second subsets of parity data for said systematic data; a second encoding unit coupled to said second antenna, said second encoding unit receiving interleaved systematic data and generating first and second subsets of parity data for said interleaved systematic data, said first subset of parity data for said systematic data and said first subset of parity data for said interleaved systematic data forming first parity data for transmission via said first antenna, a first antenna processor coupled between said first encoding unit and said first antenna and receiving said systematic data and said first parity data, said first antenna processor coding said systematic data and said first parity data in a first manner for transmission via said first antenna, said first antenna processor logically dividing said first parity data into first and second portions, transmitting said first portion of said first parity data together with said systematic data during a first transmission period, and transmitting said second portion of said first parity data during a second transmission period subsequent to said first transmission period, said second subset of parity data for said systematic data and said second subset of parity data for said interleaved systematic data forming second parity data for transmission via said second antenna, a second antenna processor coupled between said second encoding unit and said antenna and receiving one of said systematic data and said interleaved systematic data, and said second parity data, said second antenna processor coding one of said systematic data and said interleaved systematic data, and second parity data in a second manner substantially orthogonal to said first manner for transmission via said second antenna, said second antenna processor logically dividing said second parity data into first and second portions, transmitting said first portion of said second parity data together with one of said systematic data and said interleaved systematic data during said first transmission period, and transmitting said second portion of said second parity data during said second transmission period, wherein either one of said first parity data or said second parity data may be employed without an other of said first parity data or said second parity data for error correction in decoding said systematic data.
2. The system for turbo encoding with transmit diversity as set forth in claim 1 further comprising: a first multiplexer concatenating said systematic data and said first parity data for transmission via said first antenna; and a second multiplexer concatenating said interleaved systematic data and said second parity data for transmission via said second antenna.
3. The system for turbo encoding with transmit diversity as set forth in claim 1 further comprising: a first multiplexer concatenating said systematic data and said first parity data for transmission via said first antenna; and a second multiplexer concatenating said systematic data and said second parity data for transmission via said second antenna.
4. The system for turbo encoding with transmit diversity as set forth in claim 1 , further comprising: a first encoder within said first encoding unit, said first encoder receiving and turbo coding said systematic data to generate parity information for said systematic data; and a second encoder within said second encoding unit, said second encoder receiving and turbo coding said interleaved systematic data to generate parity information for said interleaved systematic data.
5. The system for turbo encoding with transmit diversity as set forth in claim 4 further comprising: a first duplicating circuit within said first encoding unit coupled to an output of said first encoder and receiving said parity information generated by said first encoder, said first duplicating circuit creating first and second copies of said parity information generated by said first encoder; and a second duplicating circuit within said second encoding unit coupled to an output of said second encoder and receiving said parity information generated by said second encoder, said second duplicating circuit creating first and second copies of said parity information generated by said second encoder.
6. The system for turbo encoding with transmit diversity as set forth in claim 5 further comprising: a first puncture unit within said first encoding unit coupled to an output of said first duplicating circuit and receiving said first and second copies of said parity information generated by said first encoder, said first puncture unit puncturing said first copy of said parity information generated by said first encoder in a first manner to create said first subset of parity data for said systematic data and puncturing said second copy of said parity information generated by said first encoder in a second manner different than said first manner to create said second subset of parity data for said systematic data; and a second puncture unit within said second encoding unit coupled to an output of said second duplicating circuit and receiving said first and second copies of said parity information generated by said second encoder, said second puncture unit puncturing said first copy of said parity information generated by said second encoder in said first manner to create said first subset of parity data for said interleaved systematic data and puncturing said second copy of said parity information generated by said second encoder in said second manner to create said second subset of parity data for said interleaved systematic data.
7. The system for turbo encoding with transmit diversity as set forth in claim 6 further comprising: an interleaver coupled to an input of said second encoding unit, said interleaver receiving and interleaving said systematic data to generate said interleaved systematic data.
8. The system for turbo encoding with transmit diversity as set forth in claim 1 , wherein said first parity data and said second parity data may be combined for decoding at a lower code rate than decoding with either said first parity data or said second parity data alone.
9. For use in a wireless communications system, a method of turbo encoding with transmit diversity comprising the steps of: sufficiently spacing first and second physically displaced antennas to produce substantially independent fading of signals received at a receiving station; generating first and second subsets of parity data for systematic data utilizing a first encoding unit coupled to said first antenna; and generating first and second subsets of parity data for interleaved systematic data utilizing a second encoding unit coupled to said second antenna; wherein said first subset of parity data for said systematic data and said first subset of parity data for said interleaved systematic data form first parity data for transmission via said first antenna and said second subset of parity data for said systematic data and said second subset of parity data for said interleaved systematic data form second parity data for transmission via said second antenna, wherein either one of said first parity data or said second parity data may be employed without an other of said first parity data or said second parity data for error correction in decoding said systematic data, logically dividing said first parity data into first and second portions; transmitting said first portion of said first parity data together with said systematic data during a first transmission period; transmitting said second portion of said first parity data during a second transmission period subsequent to said first transmission period; logically dividing said second parity data into first and second portions; transmitting said first portion of said second parity data together with one of said systematic data and said interleaved systematic data during said first transmission period; and transmitting said second portion of said second parity data during said second transmission period.
10. The method of turbo encoding with transmit diversity as set forth in claim 9 further comprising: concatenating said systematic data and said first parity data for transmission via said first antenna; and concatenating said interleaved systematic data and said second parity data for transmission via said second antenna.
11. The method of turbo encoding with transmit diversity as set forth in claim 9 further comprising: concatenating said systematic data and said first parity data for transmission via said first antenna; and concatenating said systematic data and said second parity data for transmission via said second antenna.
12. The method of turbo encoding with transmit diversity as set forth in claim 9 , further comprising: employing a first encoder within said first encoding unit to generate parity information for said systematic data; and employing a second encoder within said second encoding unit to generate parity information for said interleaved systematic data.
13. The method of turbo encoding with transmit diversity as set forth in claim 12 further comprising: duplicating said parity information generated by said first encoder to create first and second copies of said parity information generated by said first encoder; and duplicating said parity information generated by said second encoder to create first and second copies of said parity information generated by said second encoder.
14. The method of turbo encoding with transmit diversity as set forth in claim 13 further comprising: puncturing said first copy of said parity information generated by said first encoder in a first manner to create said first subset of parity data for said systematic data; puncturing said second copy of said parity information generated by said first encoder in a second manner different than said first manner to create said second subset of parity data for said systematic data; puncturing said first copy of said parity information generated by said second encoder in said first manner to create said first subset of parity data for said interleaved systematic data; and puncturing said second copy of said parity information generated by said second encoder in said second manner to create said second subset of parity data for said interleaved systematic data.
15. The method of turbo encoding with transmit diversity as set forth in claim 14 further comprising: interleaving said systematic data to generate said interleaved systematic data.
16. The method of turbo encoding with transmit diversity as set forth in claim 9 further comprising: coding said systematic data and said first parity data in a first manner for transmission via said first antenna; and coding one of said systematic data and said interleaved systematic data, and said second parity data in a second manner substantially orthogonal to said first manner for transmission via said second antenna.
17. The method of turbo encoding with transmit diversity as set forth in claim 9 , wherein said steps of generating first and second subsets of parity data for systematic data utilizing a first encoding unit coupled to said first antenna and generating first and second subsets of parity data for interleaved systematic data utilizing a second encoding unit coupled to said second antenna further comprise: generating first parity data and said second parity data which may be combined for decoding at a lower code rate than decoding with either said first parity data or said second parity data alone.
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February 1, 2001
August 3, 2004
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